The relationship between the atmospheric concentration of
cosmogenic isotopes, the change of solar activity and hence
secondary neutron flux has already been proven. The temporal
atmospheric variation of the most studied cosmogenic isotopes
shows a significant anti-correlation with solar cycles. However,
since artificial tritium input to the atmosphere due to nuclear-
weapon tests masked the expected variations of tritium
production rate by three orders of magnitude, the natural
variation of tritium in meteoric precipitation has not
previously been detected. For the first time, we provide clear
evidence of the positive correlation between the tritium
concentration of meteoric precipitation and neutron flux
modulated by solar magnetic activity. We found trends in tritium
time series for numerous locations worldwide which are similar
to the variation of secondary neutron flux and sun spot numbers.
This variability appears to have similar periodicities to that
of solar cycle. Frequency analysis, cross correlation analysis,
continuous and cross wavelet analysis provide mathematical
evidence that the correlation between solar cycle and meteoric
tritium does exist. Our results demonstrate that the response of
tritium variation in precipitation to the solar cycle can be
used to help us understand its role in the water cycle.
